Moreover, we compared the population genetic structure of N. irene with its sister species Nehalennia gracilis, which lacks female polymorphism. Remarkably, our results indicate that the overall genetic variability is three times lower in N. irene than in N. gracilis, which might be related to the availability of the species’ preferred habitat. Furthermore, haplotype AUY-922 mw and nucleotide diversity of N. irene differed considerably among sampled sites and appears to be related to the spatial distribution in female morph frequencies. In addition to previously studied selective agents, we suggest that the species’ evolutionary history, such as random genetic drift during

recolonization, may also be important in explaining the current geographical distribution of female morph frequencies. “
“Natural environmental periodicity that occurs on both the small scale like day length, or larger scale like lunar light can provide animals with valuable information about resource availability and predation risk. Such environmental cycles are often linked to the timing of reproduction.

Here, using the circulating androgen concentrations, gonadal Y-27632 cost investment patterns and detailed behavioral observations we show that wild populations of the group-living cichlid, Neolamprologus pulcher from Lake Tanganyika, have marked diurnal differences in behavior and lunar synchronicity in their reproductive physiology and behavior. Female ovarian investment peaked in the first quarter of the lunar cycle. In males, plasma steroid hormone levels and sperm swimming speed were highest at this same

lunar stage, supporting the idea that egg laying occurs during this phase and that young will emerge at full moon, perhaps because nocturnal predators can be best detected then. Female subordinate group members’ gonadal investment patterns mirrored the lunar pattern observed in dominant female breeders. In contrast, male subordinates did not show a change in gonadal investment or in steroid hormone concentrations across the lunar cycle, suggesting that female subordinates, but not male subordinates, reproduce within the social group. Neolamprologus pulcher demonstrated diurnal cycles in behavior, with higher rates MCE of feeding in the morning. Male and female breeding pairs were strongly size matched potentially as a result of size-assortative mating; also the gonadal investment of male and female mated pairs was strongly correlated indicating within-pair reproductive synchronicity. In general, this study provides evidence for the impact of environmental cues (sunlight and moonlight) on circulating hormones and reproduction in a small tropical freshwater fish. “
Canada. Given its large distribution range, historical events may be of particular relevance in explaining the observed spatial variation in morph frequencies in this species.